How are airplanes becoming greener?

Short of amping up your exercise regimen before traveling, there's not much you can do to make an airplane lighter. You can, however, bring your own stuff like a pillow, water bottle, and utensils to cut down on the disposable versions the airline will throw away after you use them. Avoid using the bathroom if possible, and definitely buy carbon offset credits to help clean up the atmosphere and your green conscience.